Medicine

Light shed on causes of cognitive troubles

Mild mental impairments in the aging are linked to common conditions.

Although some memory loss is associated with normal aging, about 22% of Americans 75 and older suffer from a condition called mild cognitive impairment, which typically goes beyond memory loss to impair the ability to speak, think and pay attention. That percentage rises to 30% by age 85.

In pinpointing for the first time how often this sometimes subtle and overlooked condition occurs in a typical population of older U.S. patients, researchers found that most of it is caused by common medical conditions.

Their findings, based upon neurological and psychiatric tests as well as brain imaging of patients, challenge the common perception that if you have mild cognitive impairment, you'll develop Alzheimer's disease, said lead researcher Dr. Oscar L. Lopez, an associate professor of neurology at the University of Pittsburgh. The reality is that, each year, only about 10% to 15% of people with mild cognitive impairment, or MCI, go on to develop Alzheimer's, he said.

"In the majority of the people, that MCI syndrome can be explained by the presence of other conditions," Lopez said, "and those conditions can be controlled or can be treated if these patients receive the proper medical care."

About 68% of mild cognitive impairment is caused by depression, strokes and tiny blockages in the brain, heart disease, high blood pressure, diabetes, the use of psychiatric medications and chronic failure of the liver or kidneys, he and his colleagues found. As a result, Lopez said, the cognitive problems are "a red flag" to treat those conditions to halt decline.

The problem is more common among African Americans (because they have higher rates of kidney failure and hypertension), those with low educational levels and those carrying a gene variation associated with late-onset Alzheimer's.

The findings, which appear in in October's Archives of Neurology, are from two studies following 3,608 men and women 75 and older at medical centers in Sacramento; Winston-Salem, N.C.; Hagerstown, Md.; and Pittsburgh for 11 years.